In a wireless communications system, a user equipment (UE) can perform wireless communication with another UE using a base station. To avoid signal interference between base stations, time synchronization needs to be implemented between the base stations. With development of services such as a multimedia broadcast/multicast service (MBMS) and coordinated multipoint transmission/reception (CoMP) in the wireless communications system, there is an increasingly high accuracy requirement on time synchronization between the base stations.
In a related technology, time synchronization between base stations may be implemented in a process of handing over UE from a source base station to a target base station. A specific process is as follows. The source base station may select a designated base station as the target base station according to a neighboring cell detection report sent by a target UE, and send a handover request to the target base station. The target base station may select, according to the handover request from a plurality of preambles (obtained from a plurality of root sequences) of a cell belonging to the target base station, a preamble as a random access preamble of the target UE. The target base station may send handover request acknowledgement information to the source base station, where the handover request acknowledgement information includes the random access preamble. After receiving the request acknowledgement information, the source base station may start to perform blind detection on the random access preamble and send a handover instruction to the target UE, where the handover instruction includes the random access preamble. Then, the target UE sends the random access preamble to the target base station, the target base station records a first moment at which the random access preamble is received, and the source base station records a second moment at which the random access preamble is detected. The target base station sends the first moment to the source base station. The source base station calculates a time difference between the first moment and the second moment, and then adjusts time of the source base station according to the time difference, so as to implement time synchronization between the target base station and the source base station.
During a process of implementing the present disclosure, the inventors find that at least the following problem exists in the related technology.
The handover request acknowledgement information sent by the target base station to the source base station indicates that the source base station performs time synchronization with the target base station. After receiving the handover request acknowledgement information, the source base station starts to perform blind detection on the random access preamble. Content of the handover request acknowledgement information sent by the target base station is relatively simple, resulting in relatively low flexibility in performing time synchronization between the source base station and the target base station in the handover process.